Did you make this instructable?

Are you using the avocado or the avocado's seed? I assume that you're using the seed since it's about the size of an egg and the avocado can be too soft to handle and will rot quickly.

The seed is lighter under the first protective layer, so perhaps you could peel it or sand it to reveal the inner pinkish layer. It will be easier to paint over it.

If you're using the avocado itself, why don't you try to 'primer' it with something? Paper mache comes to my mind - use flour, water and toilet or kitchen paper. The making of paper mache is explained here: https://www.instructables.com/id/SDSN1R0FRXUSRC3/ . After the paper mache dries it will be hard as a rock, sand it a bit and it will be very easy to paint it now.

Excellent advice talty. Actually using the whole avocado. My girlfriend is crazy about 'em so I figured why not incorporate her favourite fruit and an easter tradition into something creative/thoughtful? Probably going with the paper (of some sort) primer idea. Thanks tatly. Much appreciated.